Editor's note: several days ago we posted a final (October 2005) draft of this report. We have since come across a complete copy of the final version of the report (November 2005) which has recently been approved by NASA Administrator Michael Griffin. In order to present the most accurate version of this report, we have removed the draft version and replaced it with the final version of the report. NASA is expected to publicly release this report in early January 2006.

8. Risk and Reliability

8.1 Summary

The risk and reliability assessment of the Exploration Systems Architecture Study (ESAS) was an integral element of the architectural design process. Unlike traditional turnkey assessments used to evaluate results independently derived by designers, the risk assessment approach used in this study allowed designers to examine risk trades concurrent with the design process. This approach resulted in an architecture that met vehicle and mission requirements for cost and performance, while ensuring that the risks to the mission and crew were acceptable.

This integrated approach to risk-informed design gave designers a risk-centric view of mission architecture and vehicle design to complement their traditional performance-centric view. This complementary perspective allowed them to see, among other things, that the local risk penalties incurred with some high-performance options might produce greater reliability throughout the overall architecture. That is, as the mission architectures evolved, assessments showed that, while certain element risks might increase, the overall mission risk could decrease by choosing the right combination of these dependent elements.

Table of Contents

This large 50 MB PDF report has been subdivided into 17 PDF files - one for each of the report's 17 sections. Click on the link at the top of each section to visit a summary page and to download that section.

Editor's note: several days ago we posted a final (October 2005) draft of this report. We have since come across a complete copy of the final version of the report (November 2005) which has recently been approved by NASA Administrator Michael Griffin. In order to present the most accurate version of this report, we have removed the draft version and replaced it with the final version of the report. NASA is expected to publicly release this report in early January 2006.